Dresden 2009 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe
DS: Fachverband Dünne Schichten
DS 1: Thin Film Characterisation: Structure Analyse and Composition (XRD, TEM, XPS, SIMS, RBS, ...) I
DS 1.7: Vortrag
Montag, 23. März 2009, 11:45–12:00, GER 37
Structural and magnetic properties of CoFeB/MgO multilayers — •Kirill Zhernenkov1, Miriana Vadala1, Boris Toperverg1, Hartmut Zabel1, Hitoshi Kubota2, and Shinji Yuasa2 — 1Department of Physics and Astronomy, Ruhr-Universität Bochum 44780 Bochum, Germany — 2National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1, Umezono, Tsukuba, Ibaraki 305-8568, Japan
CoFeB/MgO/CoFeB tunnel junctions display one of the highest TMR values at room temperature[1], only surpassed by Fe/MgO/Fe(001) MTJs. In the latter case, it is argued that the giant TMR effect is due to the textured epitaxial growth properties which leads to a coherent tunneling process instead of a diffuse tunneling. However, CoFeB films are amorphous and the MgO layer is microcrystalline. Nevertheless, very high TMR values of more than 350% have been achieved. We have investigated multilayers of CoFeB/MgO fabricated by different preparation procedures and annealed at temperatures between 240 - 360°C. High resolution x-ray scattering, polarized neutron reflectivity (PNR) and MOKE measurements have been done. It was found that the multilayers have different interfacial sharpness and structural quality depending on the way of preparation. At certain conditions the interfaces remain sharp up to the highest annealing temperature, whereas recrystallization or texturization is not observed. PNR experiments indicate a dependence of the CoFeB layer magnetization upon annealing temperature and method of MTJ sample fabrication. 1. S. Yuasa and D. D. Djayaprawira, J. Phys. D: Appl. Phys. 40 (2007) R337